Using water/salt will damage the shallow-rooted blueberries AND will damage the soil.

Tilling the weeds will also damage the shallow blueberry roots AND will propagate the perennial weeds.

If you're serious about this, contact your county's Extension Service office and ask to speak with a (Small) Farm Advisor.
Locate your county's office with the map at the link below -

Here is a link that might be useful: locate your County's Extension Service office

Oy. Poison Ivy. I've only ever had luck with herbicides or digging out every single root. Since it spreads through the roots I wonder if the vinegar would work on it? Hopefully someone else will have had experience with that.

I have heard that instead of spraying herbicide, you can clip the plant and then apply a small amount of the herbicide to the clipped stalk with a Q-tip. This keeps the herbicide in the poison ivy only, and doesn't have you spraying it on your soil when you miss the leaves.

But the only truly organic method I've known is the digging. Just be sure to cover every inch of skin -- I was always amazed at how easy it was to get it when I thought "oh, I'll just make sure not to touch it even though I'm wearing shorts . . ."

Another idea -- since there are some people who don't get poison ivy, they can be hired to rip it out. We've done that before, too -- a great win/win solution.

The blueberries sound wonderful -- I'm sure you'll find a solution to the weeds!

The unwanted plants growing with those Blueberries, the "weeds", are best removed through cultivation and tilled into the soil to put the nutrients they removed back. Spraying, even with Vinegar, will still leave dead plant residues that will need to have something done with before covering with a mulch material. Some of the Blueberry growers around here simply mow between the rows of bushes to keep that unwanted plant growth somewhat under control.

There are times that I think people simply preach what they want to, not actually address the concerns of the question posed.

There is a world of difference between a cultivated and cared for patch of blueberries (or any other berry or orchard, be it I/2 acre or 200 acres), and a patch where the non desirable plants have gotten out of control.

So you want to be organic. Yet you ask the question of using a salt solution? Do you really understand what you are proposing to do, or have you established your method before you understand the question? I'm going to build a house. Do I use a hammer or a nail gun?

Where does one buy vinegar of (___) concentration? If only there were this thing where you could locate anything in the world, all while dressed in your undies. Or if only there were stores that sell products related to garden care. In the conservative social nature of the northeast, there can't possibly a place locally, be it agway or a garden center, that would cater to the desires of people who think very highly of their social, political, and environmental ideals, and have the money...and will...to spend to support them. Nope.

Note: You may want to look into what happens you burn the foliage of a perennial plant with a massive root system, and vigorous growth. Vinegar as an herbicide was never intended to deal with such a thing.

Why write a five paragraph response and not answer the questions? These are the issues you mention but didn't provide answers to:

1. This is what happens when you use salt to kill plants:

2. You might try the following resources to locate high concentration vinegar without paying shipping costs:

3. This is what happens when you burn the foliage of a perennial plant with a massive root system and vigorous growth:

There are many people on Gardenweb - not just the OP - who could be helped by this information.

I assume that the op wants an organic blueberry patch/farm.
It sounds like a tough row to hoe with the weeds and perannials. Of course the fastest and easiest way to kill poison ivy is with herbicides. Otherwise it is mowing, grubbibg, and persistence.

After working in such conditions, check yourself nightly for ticks.

to me the best way to deal with PI is paint a single leaf with Roundup. The whole plant is gone, including the roots, never to return. After that, one can be 100% organic. Spraying herbicides will inevitably kill the blueberries.

Using any glyphosate product is unacceptable to an organic grower, not just because it is a synthetic product but because of the known environmental hazards that are becoming more evident.

Here is a link that might be useful: More about glyphosate

To the OP - I feel for you! My great-uncle died last Aug, and his DD wants my help managing her blueberry patch (he used to do PYO), it's only about 1/10 acre and 1 year and it's overgrown, I can't imagine your fields!

A lot of ground to cover, but I think the only thing you can do is mow (I don't know, tilling might spread it more) and mulch thickly - even cover with plastic. How much space between rows?

All you have to do is mow it low enough to keep it knocked down, mulch to keep it from getting sun (plastic or cardboard if you can find enough and make sure to overlap the edges would be goo, to keep it from getting rain too). I have a problem with ragweed here, clear plastic seems to work better to solarize it and once the leaves are dead I can pull up the roots. Smothering it with thick wood chips didn't help - tried that in 2012 during drought and the ragweed thrived b/c it kept moisture in!

Once you think you've killed the foliage, you can remove the plastic/cardboard and start pulling up the roots - wear gloves! Then I'd put the plastic (try pro-quality landscape fabric) back on, you can mulch then with woodchips so people have something to walk on, hopefully the fabric will keep the PI down. If you skip the fabric it WILL come right back up through the woodchips and you'll have to keep pulling it.

If that's too much to handle on 1/2 acre, then constant mowing (and pulling vines if/when they start to climb the bushes) is the only thing to do. At least you don't expect anyone to be out there barefoot, right?

We are trying to go organic with no herbicides and are looking for some help on how to proceed.

How much time do you have?
How physically fit are you?

1. For the trees surrounding the blueberry patch, we are thinking of using a small tractor backhoe to scrape and get rid of the weeds.
Bad idea, because it will scrape and damage the roots of those trees.

Renting a "brush hog", which is like a super-duper lawnmower, to clear it out and then mulching it heavily will work.

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Your spoiler is the poison ivy ... removing the top is not enough, mulching it is not enough, and until you get it cleared out you can't easily work back there. And it's just as toxic dead as it is alive ... so just killing it is not enough.

Do you have the time and patience to suit up and pull ivy, bag it and dispose of it for the next few months? And repeat it next year for the sprouts coming from the roots you didn't pull?

That's where the "Tongs of Death" can come in handy. Selective application of glyphosate to just the poison ivy to kill it all the way back to the tips of its roots, then carefully removing the dead stuff by pulling it out and bagging it it for disposal.

http://www.wildones.org/learn/native-plants-and-landscaping/tongs-of-death/

Spend a while every weekend patrolling with the tongs, searching out ivy and removing the stuff you killed last week.

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You are in an area where poison ivy grows, so you have to patrol for new seedlings every year ... birds spread the seeds.

Poison ivy is one of the more challenging weeds to remove, both because it is a skin threat, and because it has a massive and herbicide resistant root system. I'd suggest mowing the areas you can reach with the mower, and then using a paint roller to apply Roundup to the ground (just as if you are painting the ground). In my opinion, this is a much more efficient use of your time and resources. You could spend man years otherwise trying to avoid using herbicide to rid the area of the pi, and might very well still not succeed. The suggestion of a brush hog, or similar mower makes a lot of sense; I use one for massively overgrown areas with great success. By the way, I've visited a fair number of organic farms over the years; Roundup is not used as part of their ongoing operations, but it is certainly the method of choice of many of them to prepare land for cultivation. In my opinion, and after having reviewed quite a bit of the literature on the subject, there are no harmful long-term (over a week) effects. If you want to experiment with how long it would take you to avoid herbicide, you might try timing yourself as you remove weeds from, say, 10 plants. Once the weeds are removed, I've had pretty good luck with a 4-6 inch layer of wood chips. Good luck
Renais

I've done a lot of different things with my blueberry patch, but the biggest mistake I made was till and mulch...
I had the most beautiful mulched patch I'd ever built and all I accomplished was providing safe haven and food for voles...
They girdled every blueberry(over 50 plants) which resulted in the death of many stems during the 2nd season, following the attack...
Now I do my best just to keep it mowed... :)

for small plants, the root system is not herbicide resistant. Of course it depends on the dose. For bigger plants, the first order of business is to cut the vines going up in the trees canopies. Their large roots will produce many suckers, but if you paint every sucker even the large roots will succumb in one year. Painting straight RU is a massive dose. I have always used it with a paint brush, never sprayed it. I bought the smallest bottle in the late 1990s, and I still use it and it will last me another ten years.

I know I'm very late to this thread, but I thought this might possibly be a good idea?

I had poison ivy under a couple of my blueberry bushes and what I did was to cover the poison ivy with a tarp. I also put a soaker hose under it to water the bush, but I often forgot to do it, and the bush seemed fine anyway.

I have to admit that this did not work as well as I hoped it would-- I think the darn poison ivy had stretched out to the sun far from my tarp.

Best of luck!